Pipe joint locator for underwater wells



P 7, 1963 0. DE VRIES ETAL 3,103,976

PIPE JOINT LOCA'IOR FOR UNDERWATER WELLS Filed May 10. 1961 2Sheets-Sheet 1 FIG. I

INVENTORS D, DE VRIES K. W. FOSTER EIR AGENT Sept. 17, 1963 13 DE v l sETAL 3,103,976

PIPE JOINT LOCATOR FOR UNDERWATER WELLS Filed May 10, 1961 2Sheets-Sheet 2 IIOV D. DE VRlES K. W. FOSTER .HMQ J% T EIR AGENT UnitedStates Patent 3,103,976 Patented Sept. 17, 1963.

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3,103,976 PIPE JOINT LOCATOR FOR UNDER- WATER WELLS Douwe de Vries,Metairie, La., and Kenneth W. Foster, Houston, Tex., assignors to ShellOil Company, New York, N.Y., a corporation ofiDelaware Filed May 10,1961, Ser. No. 109,062 7 Claims. (Cl. 166-46) This invention relates toapparatus for use in drilling offshore wells and pertains moreparticularly to apparatus adapted to be mounted adjacent to a blowoutpreventer at a well installation positioned below the surface of a bodyof water for locating pipe joints of a drill string relative to theblowout preventer when drilling an offshore Well.

In an attempt to locate new oil fields, an increasing amount of welldrilling has been conducted at olfshore locations, such for example, asthe coast of Louisiana, Texas and California. As a general rule, thestrings of casing in a well, together with the tubing string or strings,extend to a point well above the surface of the water where they areclosed in the conventional manner that is used on land wells, with aconventional wellhead assembly being attached to the top of the casing.Attempts have been made recently to provide methods and apparatus fordrilling, completing and working over a well wherein both the wellcasinghead and the various wellhead components secured thereto aresuspended therefrom and located underwater at a depth sufficient toallow ships to pass over them. Preferably, the casinghead and itsassociated equipment is located close to the ocean floor. In order todrill wells wherein the drilling wellhead assembly is positioned on theocean floor, it has been necessary to design entirely new equipment forthis purpose. Thus, during the drilling and'completion of an oil or gaswell at an offshore location in a manner described in copending patentapplication, Serial No. 830,538, filed July 30, 1959, and entitled,Underwater Well Completion Method, it is necessary to know at all timesthe position of any tool joint or coupling in the drill stem relative tothe blowout preventers.

Tool joints of a drill stern are generally larger in outside diameterand have a greater mass than the normal diameter of the rest of thedrill stem. Blowout preventers that are employed on a well forcontrolling wel-l pressures under emergency conditions are normallyprovided with closure members, such for example, as rubberfaced rams,which are designed and built to close around a tubular member of apredetermined diameter. Thus, during drilling operations, therubber-faced rams of a blowout preventer can at any time be closed in afluidtight manner around a drill pipe but not around the larger-diametertool joints thereof. It is, therefore, necessary to know the location ofthe tool joints in the drill stem closest to a blowout preventer beforeclosing the rams thereof.

In drilling land wells, it is a relatively simple matter to determinethe location of a tool joint relative to the blowout preventer on thewell since the operating platform is at a known short distance above theblowout preventer. Thus, knowing the distance between the blowoutpreventer and the operating floor and being able to judge the distancebetween the operating floor and the top of a pipe section or kelly, theposition of the tool joint nearest to the blowout preventer is known.However, in drilling at an offshore location from a floating drillingplatform or barge which moves up and down from the surface of the waterto some degree, the problem of determining the position of a tool jointrelative to a blowout preventer, which may be several hundred feet belowthe barge on the ocean floor, is much more difl'icult. In :an emergencydrilling situation requiring a prompt closure of the blowout preventers,the drilling operator may not have sufficient time to consult the vesselposition indicators, pipe string, depth indicators, etc., and make thecalculations needed to tell him whether a tool joint is between the ramsof his blowout preventer. I

It is, therefore, a primary object of the present invention to provideapparatus associated with a blowout preventer for indicating at a remotelocation the position of a tool joint relative to the rams of a blowoutpreventer.

Another object of the present invention is to provide apparatus forindicating the presence of a tool joint passing through the apparatusregardless of whether the tool joint is motionless, is moving from sideto side, or is moving axially and/or rotating.

A further object of the present invention is to provide apparatusadapted to be positioned adjacent a blowout pneventer for transmitting asignal to a point above the surface of the body of water so as toindicate the presence of tool joints passing through the apparatusregard lessof the speed at which the pipe string is moving in thesensing apparatus.

A still further object of the present invention is to provide apparatuswhich will indicate the presence of tool joints passing through theindicating apparatus without the necessity of providing feeler elementsor other contacting devices which would physically contact the pipe orthe tool joints.

Still another object of the present invention is to provide a pipe-jointsensing device adapted to be positioned outside a large-diameter pipewhile indicating movement of a pipe joint over a relatively smallvertical distance withinthe large-diameter pipe.

7 These and otherobjects of this invention will be understood from thefollowing description taken with reference to the drawing, whereiniFIGURE 1 is a diagrammatic view illustrating a floating drilling bargeanchored to the ocean floor over a drilling location while a string ofdrill pipe extends through a marine conductor pipe down through theblowout preventers in a wellhead assembly which is provided with thepipe joint locator of the present invention;

FIGURE 2 is a diagrammatic view of a wellhead installation showing twoalternative mountings of the pipe joint locator of the present inventionrelative to a blowout preventer;

FIGURE 3 is a schematic view of one form of a pipe joint locator withits indicating circuit means in accordance with the present invention;and

FIGURE 4 is a circuit diagram of another form of a circuit for a pipejoint locator employing two coi1s.- Referring to FIGURE 1 of thedrawing, a drilling barge 1 1 of any suitable fixed or floatable type isillustrated as floating on the surface of the water 12 and substantiallyfixediypositioned over a preselected drilling location by being anchoredto the ocean floor 13 by anchor lines 14 and 15 running to anchors (notshown) sunk in the ocean' floor. Equipment of this type may be used whencarrying on well drilling, well completion, or well maintenanceoperations in water varying from about to 1500 feet or more. Thedrilling barge is equipped with a suitable derrick 16 containing falllines 17 and a hoist 18, as well as other auxiliary equipment neededduring the drilling or servicing of a well, such for example, as arotary table 19. In thi-s'instance, the drilling rig is also shown asbeing provided with a traveling block '21 to -whichis secured a pair ofelevators 2 2 or other suitable means for connecting f the hoist systemto a string of pipe, such as a drill stem 23; During drillingoperations, a swivel nozzle (not shown) would be connected to the top ofthe drill stem. 3 A flexible hose 24 is provided which is adapted to besecured to the top of the drill stem or nozzle while drilling so that adrilling fluid may be pumped down through the drill stem 23. Theflexible hose 24 is in communication with a pump 25 for pumping thedrilling mud.

The derrick 16 is positioned over a drilling slot or well 26 whichextends vertically through the barge 11 in a conventional manner. Whenusing the equipment of the present invention, the slot 26 and the barge11 may be either centrally located or extend in from one edge. However,operations with the apparatus of the present invention may be carriedout over the side of the barge without use of a slot. Additionally, theapparatus of the present invention may be employed on an underwater wellinstallation when drilling wells from a fixed platform rather than abarge.

A wellhead support structure, which is represented by ahorizontally-extending support frame 27 having a casinghead 28 securedthereto and centrally positioned thereon, is illustrated as beinganchored to the ocean floor by means of a conductor pipe or surfacecasing 31 which is installed and preferably cemented in the ocean floor-13. A blowout preventer 29 is coaxially mounted on the top of thecasinghead in any suitable manner, as by bolts or by any suitableconnector 30 well known to the art. Secured to the wellhead supportframe 27 are two or more guide columns 32 and 33 having guide cables 34and 35 extending vertically therefrom to the drilling barge 11 wherethey are preferably secured to the barge by means of constant tensionwinches 36 and 37. The guide cables 34 and 35 are provided for thepurpose of guiding pieces of equipment from the barge "11 into alignmenton, or in, the casinghead 28 positioned on the ocean floor. The pipejoint locator of the present invention is positioned on a tubular member39 which is fixedly secured to the top of the blowout preventer 29 inthe arrangement shown in FIGURE 1. Additionall a wellhead connector 40is illustrated as connecting the lower end of a marine conductor pipe 41to the top of the tubular member extending vertically from the blowoutpreventer 29, in a manner described in copending patent application,Serial No. 830,538, filed July 30, 1959. However, it is to be understoodthat the use of a marine conductor pipe 41 is not essential and the pipejoint locator of the present invention may be used in any other suitabletype of a drilling Wellhead positioned below a body of water, such forexample as shown and described in U.S. Patent 2,808,230, entitledOffshore Drilling, which issued to R. C. McNeill et al. on October 1,1957.

Referring to FIGURE 2 of the drawing, the blowout preventer 29 and thewellhead connector elements 30 and 40 are shown as being provided withguide arms 42 and 43, 44 and 45, and 46 and 47, respectively. The guidearms are adapted to have their extending ends guided down through thevertical guide columns 32 and 33. Additionally, the blowout preventer 29and the wellhead connectors 30 and 40 are also provided with hydraulicpressure fluid hoses, 50 and 51, 52 and 53, and 54 and 55, respectively.Two of the tool joints 56 and 57 of the drill stem 23 are illustrated.

The pipe joint locator of the present invention is diagrammaticallyillustrated in FIGURE 3 as comprising the non-magnetic tubular member orcoil housing 60 having three coils wound thereon and axially displacedone from the other. The intermediate coil 62, or the exciting coil, isconnected to a suitable power source which is normally provided throughleads 64 and 65.=which extend upwardly to the drilling barge 11 at thesurface. The coils 61 and 63 above and below the exciting coil 62, areknown as the pickupcoils of the present system and are differentiallyconnected or oppositely wound and connected to a volt meter 66 forindicating any diiference in the mutual inductance between each of thepickup coils and the exciting coil. A voltage output signal is obtainedwhen there is a greater mass of metal passing through or positioned inone of the coils as compared to the other coil. Thus, in the event thata tool joint 56 was positioned within the coil housing 69 opposite thepickup coil 61, there would be a greater mass of metal inside pickupcoil 61 than inside pickup coil 63 so that a voltage reading would beobtained, giving an indication of the location of the tool joint 56. Inthe event that the tool joint 56 is outside both of the coils, therewould be no difference signal obtained on the indicating volt meter 66.The mutual inductance of the present system would also change as thepipe within the coils moves from side to side during drillingoperations, but since the change would be equal and opposite in bothpickup coils, there would be no change in the output signal.

The size of the coils employed may be of any suitable dimensiondepending upon the size of the coil housing 60 employed, the verticalheight of the tool joints 56, etc. For example, if pickup coils of arelatively small vertical height are employed, the spacing between thepickup coils 61 and 63 should be at least equal to the vertical heightof a tool joint 56 to pass therethrough so that there would be no chanceof a tool joint 56 being in both coils at the same time. However, in theevent that each of the pickup coils 61 and 63 extended over a verticaldistance of eight or ten inches or more, the lower edge of coil 61 andthe upper edge of coil 63 could be close together and could even overlapthe exciting coil 62, if desired. The nonmagnetic coil housing 60 isprovided with a longitudinal slot through the wall thereof which extendsvertically a distance greater than the span of the pickup coils 61 and63. This slot may be relatively small in width, say ,5 of an inch, andmay be filled with a material such as an epoxy resin. Since the slot 67would weaken the coil housing 60, the coil housing 60 could eithersurround or be encased within the tubular member 39 (FIGURE 2) extendingupwardly from the blowout preventer 29. Although the coils 61, 62 and 63have been illustrated in FIGURE 3 as being wound on the non-magneticcoil hous' ings 60, it is to be understood that they may be prewound onanother mandrel and inserted within recesses formed or cut on the innersurface of the coil housing 60.

In FIGURE 2, the tubular member 39 extending upwardly from the blowoutpreventer 29 is shown as being provided with the pickup and excitercoils 61a, 62a and 63a. The electrical leads from the coils 61a, 62a and63a are joined together in a single electrical transmission cable 68which passes upwardly to the surface along with the hydraulic pressurehoses. In this arrangement, .the tubular member 39 would be ofnon-magnetic material and would have a slot therein as described withregard to FIGURE 3. Another arrangement of the coils are shown in FIGURE2 wherein an exciter coil 62b and pickup coils 61b and 6312 are shown asbeing mounted on a non-magnetic tubular coil housing which is securedbetween the wellhead connector 40 and the rest of the marine conductorpipe string 41 so as to be retractable therewith. The electrical leadsfrom the coils 61b, 62b and 63b are combined together in a singleelectrical cable 70 which is secured to the outside of the marineconductor string 41. It is to be understood that the pipe joint locatorof the present invention could also be located below the blowoutpreventer 29, if desired.

When carrying out drilling operations while using the apparatus of thepresent invention on an underwater well drilling assembly, in the eventthat an emergency arose so that the blowout preventer 29 had to beclosed around the drill stem 23, the operator would look at the signalindicating device 66, which in this case is described as a volt meter,and would know if any signal appeared thereon. If there was no signalindicated, the operator would raise or lower the drill string 23 until asignal was obtained. This would indicate that a tool joint 56 waspositioned opposite one of the pickup coils and hence out of the way sothat the rams of the blowout preventer 29 could be closed.

FIGURE 4 illustrates a bridge circuit which could be used for coils 61aand 63a when it is not desired to use an exciter coil 62a. In this casethe two coils 61a and 63a are additively connected and compared againsteach other in a simple bridge circuit. There would be no unbalance ofthe circuit in the event that a' pipe moved from side to side in thecoils as the impedance of both coils would be influenced in thesamedirection, hence no resulting falseoutput signal.

We claim as our invention:

1. An underwater wellhead installation comprising a vertically-extendingcasinghead fixedly positioned below the surface of a' body of water,blowout preventer means having a bore therethrough'and being securedcoaxially to the top of said casinghead, vertically-extending tubularmeans having one end thereof fixedly posiitoned relative to said blowoutpreventer and coaxial with the bore therethrough,-horizontally-disposedelectrical coil means carried by said tubular means adjacent the borethereof and at a predetermined distance relative .to said blowoutpreventer, and circuit means including a current source, coil means andelectrical signal transmission means connected to said coil means andextending upwardly through said body of water, and signal indicatingmeans positioned above said body of water operatively connected to saidsignal transmission means.

'2. An underwater wellhead installation comprising avertically-extending casinghead fixedly positioned below the surface ofa body of water, blowout preventer means having a bore therethrough andbeing secured coaxially to the top of said casinghead,vertically-extending tubular means having one end thereof fixedlysecured to said blowout preventer coaxial with the bore therethrough, aportion of the length of said tubular means being made of non-magneticmaterial and forming a coil housing, horizontally-disposed electricalcoil means carried by said coil housing at a predetermined distancerelative to said blowout preventer, said electrical coil meanscomprising exciting coil means and pickup coil means for sensing anychange in the mass of a metal member disposed within said electricalcoil means, and circuit means including a current source connected tosaid exciting coil means and electrical signal transmission meansconnected to said pickup coils and extending upwardly through said bodyof water, and signal indicating means positioned above said body ofwater operatively connected to said signal transmission means.

3. An underwater wellhead installation comprising a vertically-extendingcasinghead fixedly positioned below the surface of a body of water,blowout preventer means having abore therethrough and being securedcoaxially to the top of said casinghead, vertically-extending tubularmeans having one end thereof fixedly secured to said blowout preventercoaxial with the bore therethrough, a portion of the length of saidtubular means being made of non-magnetic material and forming a coilhousing, horizontally-disposed electrical coil means carried by saidcoil housing at a predetermined distance relative .to said blowoutpreventer, said electrical coil means comprising exciting coil means andpickup coil means, said pickup coil means comprising a pair ofoppositely-wound axiallydisplaced coils mounted on said coil housing onthe wall thereof adjacent said exciting coil means for sensing anychange in the mass of a metal member disposed within said electricalcoil means, and circuit means including a current source connected tosaid exciting coil means and electrical signal transmission meansconnected to said pickup coils and extending upwardlythrough said bodyof water, and voltage signal indicating means positioned above said bodyof water operatively connected to said signal transmission means.

4. An underwater Wellhead installation comprising a vertically-extendingcasinghead fixedly positioned below the surface of a body of water,blowout preventer means having a bore therethrough and being securedcoaxially to the top of said casinghead, vertically-extending tubularmeans having one end thereof fixedly secured to said blowout preventercoaxial with the 'bore therethrough, the internal diameter of saidtubular meansbeing-substantially equal to the bore of said blowoutpreventer, said tubular means extending from the blowout preventer to apoint above the surface of the body of water, a portion of the length ofsaid tubular means being made of non-magnetic material and forming acoil housing, horizontally-disposed electrical coil means carried bysaid coil housing on the outer surface thereof at a predetermineddistance relative to said blowout;preventer, said electrical coil meanscomprising exciting coil means comprising exciting coilmeansand pickupcoil means, said pickup coil means comprising a pair of oppositely-woundaxially-displaced coils mounted on said coil housing on the wall thereofadjacent said exciting coil means for sensing any change in the mass ofa metal member disposed within said electrical coil means, and circuitmeans including a current source connected to said exciting coil meansand electrical signal transmission means connected to said pickup coilsand extending upwardly through said body of water, and voltage signalindicating means positioned above said body of water operativelyconnected to said signal transmission means.

5. A method of emergency control of an underwater well during welloperations carried out while employing a blowout preventer secured tothe underwater well and a number of pipe sections secured end-to-end bytool joints to form a pipe string extending through said blowoutpreventer upwardly to a vessel on the surface of a body of water, saidmethod comprising (a) determining at a point near the underwater wellthe presence or absence of a tool joint in a pipe string at apredetermined position relative to the blowout preventer at the well,

(b) transmitting a signal indicative of the presence or absence of atool joint at the position to a remote location above the surface of thewater,

(0) noting from said remote location above the surface of the water thepresence or absence of said tool joint at a predetermined position,

(d) disposing the pipe string vertically inthe blowout preventer so thatthe signal indicates a tool joint above and below the preventer, and

(e) closing the blowout preventer about the pipe string between two tooljoints thereof.

6. A method of emergency control of an underwater well during welloperations carried out while employing a blowout preventer secured tothe underwater well and a number of pipe sections secured end-to-end bytool joints to form a pipe string extending through said blowoutpreventer upwardly to a vessel on the surface of a body of water, saidmethod comprising (a) electrically detecting at a point near theunderwater well the presence or absence of a tool joint in a pipe stringat a predetermined position relative to the blowout preventer on thewell,

(b) transmitting a signal indicative of the presence or absence of atool joint at the position to a remote location above the surface of thewater,

(c) noting at said location on the vessel at the surface of the waterthe presence or absence of said tool joint at said predeterminedposition,

(d) moving the pipe string vertically in the blowout preventer to aposition where the signal indicates no tool joint is inside thepreventer, and

(e) closing the blowout preventer about the pipe string between two tooljoints thereof.

7. A method of emergency control of an underwater well during welloperations carried out while employing a blowout preventer secured tothe underwater well and a number of pipe sections secured end-to-end bytool joints to form a pipe stning'extending through said blowoutpreventer upwardly to a vessel on the surface of a body of water, saidmethod comprising (a) mounting a tool joint detector adjacent anunderwater well and coaxially therewith at a known distance from ablowout preventer thereon,

(b) detecting at a point near the underwater well the presence orabsence of a tool joint in a pipe string at a predetermined positionrelative to the blowout preventer on the well,

(0) transmitting a signal indicative of the presence or absence of atool joint at the position to a remote location above the surface of thewater,

(d) noting at said remote location above the surface of the water thepresence or absence of said tool joint at said predetermined position,

(e) positioning the pipe string vertically in the blow- References Citedin the file of this patent UNITED STATES PATENTS McNeill Aug. 5, 1952Gieske Ian. 4, 1955 Foerster May 31, 1960 Nerwin June 21, 1960 FOREIGNPATENTS Great Britain June 3, 1959

5. A METHOD OF EMERGENCY CONTROL OF AN UNDERWATER WELL DURING WELLOPERATIONS CARRIED OUT WHILE EMPLOYING A BLOWOUT PREVENTER SECURED TOTHE UNDERWATER WELL AND A NUMBER OF PIPE SECTIONS SECURED END-TO-END BYTOOL JOINTS TO FORM A PIPE STRING EXTENDING THROUGH SAID BLOWOUTPREVENTER UPWARDLY TO A VESSEL ON THE SURFACE OF A BODY OF WATER, SAIDMETHOD COMPRISING (A) DETERMINING AT A POINT NEAR THE UNDERWATER WELLTHE PRESENCE OR ABSENCE OF A TOOL JOINT IN A PIPE STRING AT APREDETERMINED POSITION RELATIVE TO THE BLOWOUT PREVENTER AT THE WELL,(B) TRANSMITTING A SIGNAL INDICATIVE OF THE PRESENCE OR